Operating System

Engine Management: How Computers Unlocked the Internal Combustion Engine


How did engines run before computers?

The internal combustion engine as we know it has always required some level of electronic signal to operate the ignition system. Before the 1980s when the first engine management computer was produced,  the electrical hardware on an engine was fairly rudimentary, boiling down to essentially a series of off and on switches for ignition timing. This is what’s referred to as mechanical ignition.

Mechanical ignition works by sending a charge from a battery to an ignition coil, which essentially stores a high voltage charge that discharges when provided with a path. This path is determined by a distributor is mechanically connected to the crankshaft of the engine. A distributor’s job is just as its name suggests – the rotation of the crankshaft causes the distributor to rotate, connecting the ignition coil to the individual spark plugs for each cylinder to ignite the mixture at the right time in the engine’s cycle to produce power.

Of course there are more complexities to how an engine produces power, involving vacuum lines and the workings of a carburetor and mechanical fuel pumps, however for this article we’re going to focus on electronics.

The First Computers Designed for Engines:

Electronic Fuel Injection, or EFI, has been around since the 1950s however before the mid 1970s was primarily used in motorsport due to its higher cost compared to a carburetor. Japanese companies such as Nissan were pioneers in early consumer EFI systems. The advantages of EFI over carburetors include better startup in cold conditions, as well as massively increased fuel economy. Then in 1980, Motorola introduced the first engine control unit, ECU, that would begin the computer takeover of the car industry.

An ECU replaces the direct mechanical connections with sensors that each read data from different parts of the engine, and feed back to ECU which crunches numbers and then determines how to adjust the various components of the engine to make sure it is operating within predetermined limits An Oxygen Sensor, or O2 sensor, is possibly one of the most important parts of a modern engine – connecting to the exhaust, the O2 sensor reads the levels of oxygen present after combustion. This is extremely important as it tells the ECU information on how efficient the engine is currently burning fuel. There are numerous other sensors on engines, but their jobs are all under the same umbrella: to feed information back to the ECU, so that the microprocessor can adjust timing and how much fuel is going in the engine accordingly.

Replacing the mechanically driven timing of early engines allows for a wider range of adjustability and control to ensure the engine is running right. This led cars to burn gas much cleaner and become much more efficient in general. As technology progressed, engine management became even more advanced, allowing for yet more meticulous control, as well as added safety measures. But what else did this computer-powered control do for the automotive industry?

Improvements in Performance

Engine Tuning

With ever increasing processing power, the computers in cars advanced just as quickly as any other computers: exponentially. More efficiently controlling fuel and timing quickly led to tuning for maximum power and response. EFI, and direct injection increased the throttle response, and further tuning could be done to make the car have a wider powerband – a term used to refer to the range of revolutions per minute (RPM) where an engine was making usable power. Manufacturers, realizing the extensive power of ECUs, started building mechanical parts around them to utilize their strengths. Below is a list of variable timing technologies used by several different companies:

  • Variable Valves/ Variable Cam Design
    • Honda VTEC (Variable Valve Timing and Lift Electronic Control)
    • Mitsubishi MIVEC (Mitsubishi Innovative Valve timing Electronic Control System)
    • Toyota VVT-i (Variable Valve Timing with intelligence)
    • Nissan VVL/VVT (Variable Valve Lift/ Variable Valve Timing)

While differing in name and how they are applied, these systems all boil down to controlling the engine timing at different engine speeds (RPM). The word ‘variable’ stands out in all of these, and is possibly the most powerful tool that advanced engine tuning enables. In this case, variable refers to the ability to change the behavior of the engine’s valves and camshafts (a long rod at the top of an engine that tells the valves when to move). As the engine speed increases, what might have been a good design at lower RPM soon starts to fall short, and this is what causes the powerband to drop off. Being able to alter the timing of the engine allows for better high and low end performance, as manufacturers essentially have the opportunity to design their engine for both, and use the ECU to switch modes at the optimal time.

Looking Forward


Most people think of hybrids as the Toyota Prius, something designed with pure efficiency in mind, however some supercar companies have taken hybrid technology and adapted it for performance. Supercars such as the McLaren P1 and Porsche 918 utilize electric engines to compliment the power of the conventional combustion engine. Managed by an advanced ECU, the electric engines are used to provide immediate power while the gas engine is accelerating into its powerband. While the electric engines can be used separately in place of the gas engine, they mainly serve to further fill in the gap that the variable timing technology we talked about previously could not. As regular hybrid technology continues to advance, we can expect to see the same with respect to response and performance.


While engine efficiency is still being improved, the means to do so are based on these core engine technologies and their supporting computer systems. Now, manufacturers have once again started producing supporting components to utilize the ECUs ability to process data.